Compared to quinolines, isoquinolines are also prominent structural motifs present in many biologically significant natural and synthetic compounds. Some well-known isoquinoline alkaloids include the anticancer and anticonvulsant berberine, the vasodilator and antispasmodic drugs papaverine and emetine. In addition to naturally occurring isoquinolines, synthetic analogs have also shown significant biological activity.
Pyrrolines, also called dihydropyrroles, are obtained from aromatic pyrroles by hydrogenation. 1-pyrroline is a cyclic imine, while 2-pyrroline and 3-pyrroline are cyclic amines.